Four people were killed, including an off-duty New York City police officer, when a gunman opened fire in an office tower before fatally shooting himself, officials said.

Midtown Manhattan was somber and on-edge after a mass shooting at an office tower left four people and the gunman dead, including Blackstone Inc. executive and a New York City police officer.

Monday’s mass shooting in Midtown Manhattan claimed the life of Wesley LePatner, a 44-year-old executive at Blackstone, the company confirmed Tuesday morning. LePatner was among four victims killed at 345 Park Avenue when a lone gunman stormed the office building,

Multiple people were killed in a shooting Monday in a corporate office building in Midtown Manhattan, according to media reports. The New York Police Department posted on X that the scene “has been contained and the lone shooter is dead.”

Investigators are combing through evidence in the wake of New York City’s deadliest mass shooting since 2000, trying to figure out more about the gunman who opened fire Monday in Midtown, killing four people,

Shane Tamura, the suspect in the deadly shooting in Midtown Manhattan, carried a note in his pocket claiming he suffered from CTE and also made references to the NFL, police sources told ABC News.

A note written by the shooting suspect was found at the midtown Manhattan office building scene where he killed four people, including an NYPD officer, and himself a day ago, officials familiar with the investigation said overnight.